Combustion apparatus



K- B. OLSSON Aug. 6, 1968 COMBUSTION APPARATUS 2 Sheets-Sheet 1.

Filed May 25, 1967 INVENTOR. Kan-L B602 OLsson BY PM 1 -Aug. 6, 1968 K- B. OLSSON COMBUSTION APPARATUS 2 Sheets-Sheet 2 Filed May 25, 1967 INVENTOR. Karl, Bdr e OLsson J K PaA/Lw United States Patent 3,395,966 COMBUSTION APPARATUS Karl Borje Olsson, Smedjevagen 9, Nacka, Sweden Filed May 25, 1967, Ser. No. 641,282 Claims priority, application Netherlands, May 27, 1966, 6607422 Claims. (Cl. 43122) ABSTRACT OF THE DISCLOSURE Combustion apparatus in which a mixture of air and fuel is sucked through an inlet system to a combustion chamber and the combustion gases leave through an exhaust duct at super-atmospheric pressure. A gas leakage duct surrounds the exhaust duct to form a leakage collecting chamber which through a conduit is connected to the inlet system and a pressure responsive member actuating an alarm device and/or a member for stopping the apparatus when gas leakage occurs.

The present invention relates to combustion apparatus in which a mixture of fuel and air is sucked through an inlet to a combustion chamber, from which the gases are exhausted at a super-atmospheric pressure through an exhaust duct.

Those portions of the exhaust duct which are exposed to the ambient atmosphere or to spaces communicating therewith involve a possibility of leakage of exhaust gases which thus may poison the atmosphere for instance in a building where people live.

The general object of the invention is to provide simple means which indicate such leakage or stop tne combustion apparatus when such leakage of exhaust gases possibly would occur.

To this end the combustion apparatus according to the invention is characterized in that the exhaust duct is enclosed in a collecting duct forming a gas leakage chamber which through a conduit is connected with the inlet system of the apparatus at a place where vacuum is prevailing and with a member responsive to changes in the gas pressure in said conduit due to leakage in the exhaust duct. The gas pressure responsive member may upon leakage actuate an alarm device such as a lamp or ringing bell and/or may actuate any control member for the air or fuel supply to the apparatus or the electric ignition system, if such is employed, so as to stop the operation of the combustion apparatus.

The invention will be described more in detail with reference to the accompanying drawings illustrating an embodiment of the invention in connection with an apparatus for pulsating combustion of tne type which is disclosed in detail in US. Patent No. 3,267,986.

FIG. 1 is a partially sectioned elevational view of the combustion apparatus, having a first and second combustion chamber.

FIG. 2 is a diagrammatic section of a boiler in which the apparatus according to the invention is employed as a heating source and at the bottom of which is provided a cylindrical container forming an expansion chamber for the exhaust gases from the apparatus.

FIG. 3 is a diagrammatic cross sectional view of the boiler in FIG. 2.

FIG. 4 is a diagram of an automatic control system which includes a device for stopping the operation of the apparatus when exhaust gas leakage occurs.

As shown in FIG. 1 the combustion apparatus has an inlet 20, a first and second combustion chamber 21 and 22, respectively, and an outlet 23 to which an exhaust duct 24, 25 (FIG. 2) is connected.

At the end of a non-return valve 26 in the inlet there is secured a socket supporting a coaxial electric heating wire coil 27 which is employed as an ignition member for starting the apparatus. The electric wires to the coil are diagrammatically indicated by 28.

This coil 28 is merely switched on for heating purposes during a starting period of maximum a few minutes.

A further detail to be noted in FIG. 1 is a conduit 29 which is connected to the inlet 20 but may be connected to any other place which is at sub-atmospheric pressure due to the suction in the inlet 20 upon operation of the apparatus. The function of this vacuum conduit will be explained below.

The apparatus in FIG. 1 may be used for heating water in a boiler 30. The exhaust duct 24 from the apparatus is connected to an expansion chamber 31.

This expansion chamber is cylindrical as shown in FIGS. 2 and 3. The end portion 32 of the exhaust duct has a greater diameter than the duct 24 to form an end piece which extends substantially tangentially through the wall 33 of the chamber 31 and has its end located near to or in a plane at right angles to the tangential direction and through the central axis of the chamber 31. Thereby, the exhaust gases will enter the chamber to provide a rotational flow which is important for the operation of a pulsating combustion apparatus. The pulses generate an alternating positive and negative pressure. By the rotation referred to above the gases are recirculated to pass the end of 34 of the end portion 32 from behind so that the negative phases of the pulsating flow will be partly or completely equalized. This renders it possible to employ a rather great resistance in the following exhaust duct, which means that the muffler 34 may have a small size. The gases enter the muffler through a region of small holes at the left end 35 of the muffler and leave the mufiier through the exhaust duct 25 surrounded by the leakage collecting duct 2511. This duct communicates through holes with the leakage collecting space below the cylinder 33, which space is closed by transverse walls 36, above which is water, and a half cylindrical shell 37. Alternatively, the mufiler may be located coaxially after the cylindrical chamber 31 and is then preferably of an axial through-flow type.

FIG. 4 illustrates a preferred circuit including control members such as a switch 38 with a switch lever 39 resting in closed position on a bimetallic spring 40 heated by a wire 41 upon starting the apparatus. After a predetermined period the bimetallic spring 40 will be in a position releasing the lever 39.

The transformer of the circuit is denoted by 42. The heating wire coil 27 is through the wires 28 connected to the transformer 42 as shown.

A thermostat 43 and an electrically driven fuel pump 44 or electromagnetic valve and a switch 45 are also included in the circuit.

The thermostat 38 will connect the circuit to the net line 46 when the temperature of the medium to be heated falls to a certain value, and Will disconnect the circuit when the temperature has increased to a certain value. At the same time the pump 44 is started or stopped, respectively.

The switch 45 has a lever 47 actuated by a pneumatic bellows 48 which through conduit 29 is connected to receive vacuum from the inlet 20 and is further connected through a conduit 49 with the semi-circular leakage receiving chamber 37 located below the expansion chamber 31 in FIG. 3, said leakage chamber communicating with the leakage conduit 25a surrounding the exhaust duct 25. When the apparatus is started the vacuum created in conduits 29, 49, 37, 25a will urge the bellows to contract so that the lever 47 will follow this movement and break the voltage to the heating wire 27. Should the apparatus fail to start the bimetallic spring 40 will after a certain time release switch 39 and break the voltage to the pump 44 to stop the supply of fuel.

Should any leakage occur in the exhaust gas system, the vacuum in conduit 49 and passages connected therewith will be reduced so that the bellows 48 operates the switch 45 to close the circuit. Accordingly, the wire 27 is connected, but after the predetermined starting period the bimetal 40 will again release the switch 38 to stop the pump 44 or close the corresponding electromagnetic valve. Accordingly, the conduits 29, 49, 37, 25a and the bellows 48 form a simple and reliable guard for stopping the apparatus upon leakage in the exhaust gas system.

Although the invention has been described as utilized for actuating a specific electric control circuit it will be understood that a pressure increase in the vacuum system formed by the conduits 29, 49 and 25a due to any leakage in the exhaust system may be utilized to actuate any suitable gas pressure responsive member to effect an alarm such as switching on an alarm lamp or ringing bell and/ or actuating any suitable control member for stopping the operation of the apparatus. The conduit 29 must not be connected directly to the inlet 20 but may be conneced to any other place in the inlet system such as the air cleaner where a subatmospheric air pressure is prevailing dut to the suction in the inlet 20.

What I claim is:

1. A combustion apparatus for a mixture of air and fuel, comprising a casing (30) for enclosing the combustion apparatus;

a suction inlet system (20);

a combustion chamber (21, 22); and

an exhaust duct (24, 25) extending through the wal of said casing (30);

a part (25) of the length of said exhaust duct (24, 25) outside the casing being enclosed in an outer duct (25a) forming a closed gas leakage-collecting chamber;

conduit means (49, 29) by which said gas leakagecollecting chamber is connected with said suction 4 inlet system (20) wherein a sub-atmospheric pressure prevails upon operation; and

a gas pressure-responsive member, having a closed chamber (48) connected by said conduit means with said gas-collecting outer duct (25a), said chamber 48 having a movable wall which is moved in response to changes in the gas pressure in said conduit means due to leakage of exhaust gases into said gas-collecting outer duct.

2. A combustion apparatus according to claim 1, which includes a fuel supply pump, and in which the drive of the apparatus is controlled by electric components including an electric motor for driving said fuel supply pump, the electric components being connectable to a source of electric current by means of a switch which is operable by said gas pressure responsive member to disconnect the electric current source when gas leakage occurs in said outer gas collecting duct.

3. An apparatus according to claim 1, wherein said gas pressure responsive member is a pneumatic bellows.

4. An apparatus according to claim 1, wherein said gas pressure responsive member when normal suction pressure is reached during the starting period, is provided to actuate a switch for effecting disconnection of the electric control circuit for an electric heating wire disposed in the combustion chamber of the apparatus.

5. An apparatus according to claim 4, wherein a bimetallic operated switch is provided to be influenced by an electric heating current during the starting period for a predetermined period which results in that the bimetallic operated switch is actuated to disconnect the voltage to the igniting wire after said predetermined period.

References Cited UNITED STATES PATENTS 7/1965 Haag 1584.192 8/1966 Kitchen 158-4192 

